Fault diagnosis system for series compensated transmission line based on wavelet transform and adaptive neuro-fuzzy inference system

This paper proposes a new fault diagnosis approach based on combined wavelet transform and adaptive neuro-fuzzy inference system for fault section identification, classification and location in a series compensated transmission line. It performs an effective feature extraction approach based on norm entropy in order to obtain the features represented main frequency, harmonic and transient characteristics of the fault signals. The proposed method uses the samples of fault voltages and currents for one cycle duration from the inception of fault. The feasibility of the proposed method has been tested on a 400 kV, 300 km series compensated transmission line for all the ten types of faults using MATLAB/Simulink for a large data set of 23,436 fault cases comprising of all the 10 types of faults. Fault signals varying with fault resistance, fault inception angle, fault distance, load angle, percentage compensation level and source impedance are applied to the proposed algorithm. The results also indicate that the proposed method is robust to wide variation in system conditions and has higher fault diagnosis accuracy with regard to the other approaches in the literature for this problem.     

Effects of blended vegetable‐based cutting fluids with extreme pressure on tool wear and force components in turning of Al 7075‐T6

In this study, performances of four different types of vegetable‐based cutting fluids (VBCFs) over a commercial mineral cutting fluid were evaluated for machinability of Al 7075‐T6. Lubrication properties of VBCFs were improved with additive of extreme pressure. Cutting force and tool wear data were obtained for performance analyses of cutting fluids during longitudinal turning of Al 7075‐T6. Cutting, feed and radial forces indicated 1.70–38.25% improvements for VBCFs over the commercial mineral cutting fluid. The lowest average values of flank and nose wears obtained with blended cutting fluid containing 12% of extreme pressure were 0.09 and 0.10 mm, respectively, whereas these values for the commercial mineral cutting fluid were 0.18 and 0.15 mm. The scanning electron microscope results showed adherence of workpiece material occurred on rake and flank faces, and flank and nose wears were the dominant wear modes. It was found that performances of VBCFs during turning of Al 7075‐T6 were better than that of the commercial mineral cutting fluid. Copyright © 2012 John Wiley & Sons, Ltd.     

Surface coated iron particles via atom transfer radical polymerization for thermal–oxidatively stable high viscosity magnetorheological fluid

A surface grafting technique for poly(2‐fluorostyrene) onto iron particles via atom transfer radical polymerization (ATRP) is described. Grafted poly(2‐fluorostyrene)–iron particles were synthesized by immobilizing 2‐4(‐chlorosulfonylphenyl)‐ethyltrichlorosilane to the iron particles through the covalent bond of a silanol group, followed by the polymerization of 2‐fluorostyrene monomer. The grafted polymer–iron particles display a higher thermal transition temperature compared to bulk polymer because the covalent bond between the polymer backbone and the surface of the iron particles restricts the molecular mobility. The molecular weight of the synthesized poly(2‐fluorostyrene) has been measured and it has a narrow molecular weight distribution (M_w/M_n < 1.1). From thermogravimetric analysis, the thermal stability of poly(2‐fluorostyrene) is superior to polystyrene. Also, the high viscosity magnetorheological fluid (HVMRF) prepared from surface coated iron particles has excellent thermo–oxidative stability, having nearly constant viscosity. These materials exhibit a large increase in shear yield stress for the off‐ and on‐state as compared to a benchmark high viscosity magnetorheological fluid (HVMRF) and ‐coated iron particle HVMRF. In addition, this type of fluid eliminates iron particle settling which is a common problem found in traditional magnetorheological fluids (MRFs). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Understanding Tomato Peelability

Approximately 75% of all tomatoes in the United States are consumed as processed and 25% as fresh. One of the first steps during processing involves removal of the peel and, unfortunately, more than 25% of the fruits (as measured by total weight) can be lost due to overpeeling. Additionally, conventional peeling applications have a negative environmental impact. Given the great potential economic benefits, many scientists have conducted research to attempt optimizing or predicting peeling performance when processing tomatoes. The literature regarding tomato peelability is contradictory in many cases; and several topics have been subject to ample debate over the years. Divergent conclusions are probably not due to faulty investigations, but rather to the extreme variability found among tomato cultivars, the effect of growing seasons, and maybe even the effect of climatic conditions on the day of harvest or during transportation to the processing plants. This review provides an in‐depth background needed for a better understanding of tomato physiology, maturation, and composition, as these could possibly influence the ease of peeling or “peelability.” The research studies directly involved with peeling tomatoes and predicting peelability are discussed in this paper as well. Different peeling methods, peeling grading scales, and fruit tagging procedures are presented, as well as experiments evaluating the effect that fruit defects, maturity, growing conditions, and other factors can have on the ease of peeling. Novel approaches for peelability prediction by means of spectroscopic and magnetic resonance technology are also discussed in this review.     

Simulations of mass attenuation coefficients for shielding materials using the MCNP-X code

In this paper,mass attenuation coefficients of concrete,bricks and cement plaster,as shielding materials,are calculated at 59.5,356,662,1173,1274 and 1333 keV by using the MCNP-X (version 2.4.0) code.The numerical simulation results are compared with previous Monte Carlo studies,experimental results and XCOM data.The effects of barite on mass attenuation coefficients are investigated.The mass attenuation coefficients increase with the barite content.Thus,our results agree well with experimental studies on gamma ray shielding of barite.It is flexible for the MN method to change the barite rates in material by small increments,which is experimentally difficult.Also,modeled geometry can be used for future approaches such as new designs and new structures especially in investigating new barite-containing materials to build nuclear reactors or high-energy radiation therapy facilities.     

Thermodynamic analysis of an existing coal-fired power plant for district heating/cooling application

In a conventional coal-fired power plant, which is only designed for electricity generation, 2/3 of fuel energy is wasted through stack gases and cooling water of condensers. This waste energy could be recovered by trigeneration; modifying the plants in order to meet district heating/cooling demand of their locations. In this paper, thermodynamical analysis of trigeneration conversion of a public coal-fired power plant, which is designed only for electricity generation, has been carried out. Waste heat potentials and other heat extraction capabilities have been evaluated. Best effective steam extraction point for district heating/cooling system; have been identified by conducting energetic and exergetic performance analyses. Analyses results revealed that the low-pressure turbine inlet stage is the most convenient point for steam extraction for the plant analyzed.     

Solar Cells with Enhanced Photocurrent Efficiencies Using Oligoaniline‐Crosslinked Au/CdS Nanoparticles Arrays on Electrodes

Different configurations of CdS nanoparticles (NPs) are linked to Au electrodes by electropolymerization of thioaniline‐functionalized CdS NPs onto thioaniline‐functionalized Au‐electrodes. In one configuration, thioaniline‐functionalized CdS NPs are electropolymerized in the presence of thioanline‐modified Au NPs to yield an oligoaniline‐crosslinked CdS/Au NPs array. The NP‐functionalized electrode generates a photocurrent with a quantum yield that corresponds to ca. 9%. The photocurrent intensities are controlled by the potential applied on the electrode, and the redox‐state of the oligoaniline bridge. In the oxidized quinoide state of the oligoaniline units, the bridges act as electron acceptors that trap the conduction‐band electrons that are transported to the electrode and lead to high quantum yield photocurrents. The reduced π‐donor oligoaniline bridges act as π‐donor sites that associate N,N′‐dimethyl‐4,4′‐bipyridinium, MV²⁺, by donor/acceptor interactions, K_a = 5270 M^?1. The associated MV²⁺ acts as an effective trap of the conduction‐band electrons, and in the presence of triethanolamine (TEOA) as an electron donor, high photocurrent values are measured (ca. 12% quantum yield). The electropolymerization of thioaniline‐functionalized Au NPs and thioaniline‐modified CdS NPs in the presence of MV²⁺ yields a MV²⁺‐imprinted NP array. The imprinted array exhibits enhanced affinities toward the association of MV²⁺ to the oligoaniline π‐donor sites, K_a = 2.29 × 10⁴ M^?1. This results in the effective trapping of the conduction‐band electrons and an enhanced quantum yield of the photocurrent, ca. 34%. The sacrificial electron donor, TEOA, was substituted with the reversible donor I₃^?. A solar cell consisting of the imprinted CdS/Au NPs array, with MV²⁺ and I₃^?, was constructed. The cell generated a photocurrent with a quantum yield of 4.7%.     

Overview of Amorphous and Nanocrystalline Magnetocaloric Materials Operating Near Room Temperature

The observation of a giant magnetocaloric effect in Gd₅Ge_1.9Si₂Fe_0.1 has stimulated the magnetocaloric research in the last two decades. However, the high price of Gd and its proclivity to corrosion of these compounds have prevented their commercial use. To reduce raw materials cost, transition metal-based alloys are investigated to replace rare earth-based materials. Environmental considerations, substitution for scarce and strategic elements, and cost considerations all speak to potential contributions of these new materials to sustainability. Fe-based soft amorphous alloys are believed to be promising magnetic refrigerants. Efforts in improving the refrigeration capacity (RC) of refrigerants mainly rely on broadening the magnetic entropy change. One promising technique is to couple two phases of magnetic materials with desirable properties. Second is the investigation of nanoparticle synthesis routes, with ball milling being the most widely used one. The motivation for the nanoparticles synthesis is rooted in their inherent tendency to have distributed exchange coupling, which will broaden the magnetic entropy curve. As proven with the cost analysis, the focus is believed to shift from improving the RC of refrigerants toward finding the most economically advantageous magnetic refrigerant with the highest performance.     

Mechanical and Antibacterial Properties of Injection Molded Polypropylene/TiO2 Nano-Composites:Effects of Surface Modification

Polypropylene (PP)/titanium dioxide (TiO2) nano-composites were prepared by melt compounding with a twin screw extruder. Nanoparticles were modified prior to melt mixing with maleic anhydride grafted styrene-ethylene-butylene-styrene (SEBS-g-MA) and silane. The composites were injection molded and mechanical tests were applied to obtain tensile strength, elastic modulus and impact strength. Antibacterial efficiency test was applied on the injection molded composite plaques by viable cell counting technique. The results showed that the composites including SEBS-g-MA and silane coated TiO2 gave better mechanical properties than the composites without SEBS-g-MA. Antibacterial efficiency of the composites varied according to the dispersion and the concentration of the particles and it was observed that composites at low content of TiO2 showed higher antibacterial property due to the better photocatalytic activity of the particles during UV exposure.     

News from the field: Visual planning and urbanism in the mid‐twentieth century conference,Newcastle, UK, 11–13 September 2007

Gjirokastra, a century-old small city in southern Albania (now a UNESCO World Heritage site), provides an outstanding example of a Classical and Late Ottoman urban centre. At the same time, it is a special example of urban and architectural design based on self-defence by individual family units. Through an excursion of Gjirokastra's residential neighbourhoods, this article discusses how defence concerns guided its urban morphology and building typology until the collapse of the Ottoman Empire. The idea of war, feuds, and fear has pervaded the residents' self-identity for centuries. The military character of their houses owes much to the local ‘warrior’ mentality that prevailed in times of war and peace.